History of the 1978 UC Torana
Overview
Holden took the LX and gave it a heavily revised front end appearance and some reworking at the rear to come up with the UC Torana in March 1978. That was the good news. The bad news was the dropping of the V8 engine. Though it was obviously secret at the time, Holden was planning to release the Commodore just six months later, and it came with V8 options. Many street machiner has overcome the problem by installing a V8. As mentioned, the carryover of the rear floor plan from the A9X means that a large Salisbury diff can be fitted at the same time. The stock diff was the newly introduced small Salisbury. Holden offered four wheel disc's as an option on the UC and it makes sence to buy one with that stopping system even if your not planning the diff conversion.
As well as the reworked exterior, the interior received a full network with less utalitarian dash than what was sold in the LH and LX. Most manual cars came with a four speed floor change gear box, although some base Torana S cars came with a three speed column change.
The sedans originally came as Torana S or SL, a Torana Deluxe joining the range later as an option on the SL. The hatches came as SL and SL/E and again you could specify an SL Deluxe. The four cylinder cars were again called sunbird. They used an Australian designed cour from mid 1978. It was virtually a 2850 six with two few cylinders lopped off and was almost as bad an engine as the unloved Opel four...
There was also sports UC released called the SL/T standing for Sports Luxury/Turbo. This was a 6 cylinder Turbo that was able to beat the LX A9X V8 from 0 - 60 mph and on the quarter mile. The only place that the SL/T was lacking was the take off where the V8 had the power at lower range of rev's and the SL/T stuggled slightly. If this has taken you interest read on as I have a personal account of a fellow Torana nut about his SL/T. He contacted me with some great detailed info on this model which has been much of a mystery to the majority of the Torana community for many years.
I quote from the info that he kindly forwarded to me:
"The UC Torana SL/T option. I've owned one since 1979. They were never produced as an official GM-H model, but were a factory sanctioned modification by Normalair-Garrett Manufacturing in Melbourne, and had full warranty and full emission gear. Essentially they were pre-production prototypes of a car with would most likely have been a factory option if the Torana had not been cancelled.
All you needed was factory ordered UC with a 3.3 liter (red motor) optioned with M20 gearbox, GU4 (3.08) or the 2.73 diff, 4 wheel disc brakes, and heavy duty radiator. The cars went straight from GMH to the NGM mini-assembly line. The SL Hatchback I ordered with no options except the mandatory items for the turbo installation, a LH external mirror, a SL/R style GMH sports steering wheel, and rust-proofing cost $7800, and the turbo modifications added another $2000 to the price. NGM handled the warranty on the drive train, and GMH handled warranty on everything else. Most of them were ordered through Sutton Motors in Sydney, but mine came through Zupps in Brisbane. Extra tire/wheel choices and aftermarket bodywork kits were also offered by NGM.
A delay in manufacture of my car by Holden due to a backlog of orders and then the Christmas shutdown, and a decision to re-engineer the turbocharger package, resulted in the time period from ordering at the dealer to delivery being just under 10 months. The previous installation had shown deficiencies, and the revised installation needed new parts and castings to be fabricated. My car sat in their factory for months while the new parts were designed. Years later, I was shown photographs of the process of the turbocharger installation on my car, as it was the first of the new series, and became the benchmark installation for other companies installing the same turbocharger kit installation.
The NGM "Strata 2a" installation kit consisted of an AirResearch T04B turbo with a wastegate set to 12-13 psi (achieved at 2100 RPM under full load) drawing through a modified 1.75" SU carburettor. A larger fuel line and fuel pump were fitted. Except for a drop in compression ratio to 7.5:1, achieved by a spacer between the head and block, the internals of the engine were untouched.
The modifications gave roughly 80% increase on stock power. They would out run an A9X to 60 mph, keep up with an XU-1 in the 1/4 mile, and mine was still accelerating at the stock red motor redline (i.e. valve bounce) in top gear at 130 mph. (A9X, 125 mph, 15.8 sec standing quarter, XU1 15.5 SEC, 125 MPH)If you kept the stock wheels and hub-caps, and didn't fit any fibreglass body add-ons, the only give-away was a 2.5 inch exhaust pipe. I have heard of one that was fitted with Sunbird badges, hub-caps, and exterior trim.
The cars were certainly not fully developed and were a maintenance nightmare.
The stock manifold gasket couldn't take the boost, and was a major job to replace. I made a custom set of modified spanners and allen keys to remove the manifold nuts and studs. It's easier to replace the manifold gasket if you pull all the studs, slightly separate the manifolds from the head enough to remove and replace the gasket and then put the studs back in. Until I had a quick disconnect fitting fitted into the exhaust pipe where it curves under the firewall, it was easier to replace the starter motor by removing the gearbox and bellhousing than it was to remove the manifolds and turbo plumbing to get to it.
Starter motors were a problem because the heat caused problems with some plastic insulation, and hot starts required a lot of cranking. The needle and seat in the SU carburettor couldn't resist the fuel pressure from the oversized fuel pump, and also couldn't resist the fuel line pressure build up from the hot engine when the car was parked. There was no problems with hot starting unless it was attempted in a window between 20 minutes and an hour after the engine was shut down. A hot start in that window required at least a 30 second cranking with the throttle fully open to clear the super rich fuel/air mix from the intake manifold and cylinders. It took me 3 years to master the hot start problems and another 2 years to find a solution. This problem apparently didn't happen on the NGM development car as it had an A9X hood scoop to vent the hot underbonnet air, but every other owner without the scoop experienced it. A heat shield under the SU carburettor, rerouted fuel lines, and a fuel pressure regulator set to 2 psi eventually solved this problem for me and increased both fuel economy and idle smoothness. Later model NGM Turbo Commodores used a different carburettor and were fitted with a variety of different design bonnet vents.
Cooling the engine was another real problem. I found that in Queensland, the heavy-duty radiator (from the previous model V8s) and the stock fan just wasn't good enough, and would lead to major overheating in city traffic. A single 12" electric fan was also insufficient, and eventually I fitted twin 12" electrics and this helped. The engine was delivered with an unmodified distributor and the stock ADR27a 6 degrees advance, which could be increased to 9 degrees before detonation under boost. An aftermarket water injection kit was fitted to allow further ignition timing advancement to 13 degrees with water injection applied at 4psi boost.
Oil quality and temperature was even more critical. I added a V8 sized oil cooler just to cool the oil feed to the turbo bearing. Without the add-on cooler, even if you'd followed the correct engine cool down procedure, you'd still need to replace the turbo bearings every 9- 12000 miles or so.
The lowered compression ratio meant that there was less power than stock until the boost arrived. That plus the taller than stock differential put extra load on the clutch. A 1-tonner clutch was good for less than 20,000 km before it slipped whenever there was positive manifold pressure. I went through a series of clutches from the 1-tonner clutch and pressure plate, to a strengthened 1-tonner pressure plate tor the dual axle 1-tonners, to a dual spring 1-tonner pressure plate to a 1 tonner pressure plate with a ceramic faced clutch plate (very nasty and very noisy, but it didn't slip until it had eventually worn a 5mm depression in the flywheel and pressure plate faces), and now I am running the very last available matched PBR Turbo clutch kit that was found still sealed in the back of a warehouse.
Between ordering and delivery, in Queensland they changed the law regarding aftermarket turbochargers, and my car became illegal just before delivery. It may have been legal, but they required me to present the car for inspection before they would make a decision. I declined their kind offer, and after 23 years, I still have not visited them.
Currently the car is off the road while it receives it's second refreshing. In 1988, I lost a cylinder (number 5 like all Holden red motors) due to cracks in both compression rings on that piston. All the other pistons had at least one cracked ring, so it was probably the end result of overheating and detonation years before. The engine received +0.030" REPCO Bathurst XU1 pistons (drilled oil holes behind the oil rings instead of slots), line boring, yella terra head, roller rockers, turbo grind cam, balancing, competition bearings, etc. This time around, I'm not doing a major engine rebuild, just a lot of little jobs. The original sump was damaged beyond repair during the previous engine rebuild while attempting to properly fit the drain line from the turbocharger (NGM did a poor job and it always leaked) so a replacement sump was obtained from a wreckers. This sump turned out to have damaged threads on the drain plug which have finally gone past the point of no return. The diff is now very noisy, and the brake disc rotors need to be replaced. If I can find the cash, I am considering eventually replacing the engine with a 3.8 V6, but for the moment it's just a case of fixing the sump, and replacing all the hoses, and doing a lot of little niggling things.
As had happened with the small Torana range (LC to TA), the last days of the LH to UC series cars passed with more of a bang than a whimper. The serious design work was going into the Commodore and the Torana became something of an afterthought. Which is a rather sad thing for a car which will go down in history as one of the most significant Aussie machines of all time."
